Preparation of a variety of fluoroalkyl end‐capped N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide oligomer/silica nanocomposites possessing no weight loss characteristic at 800°C

A variety of fluoroalkyl end‐capped N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide oligomer [R_F‐(DOBAA)_n‐ R_F]/silica nanocomposites, in which the oligomer contents are 18–96%, were prepared by reactions of the corresponding fluorinated oligomer with tetraethoxysilane and silica nanoparticles under alkaline conditions. Each fluorinated oligomer/silica composite thus obtained is nanometer size‐controlled very fine particles (22–68 nm) possessing a good dispersibility and stability in a variety of solvents including water. Interestingly, the weight loss of R_F‐(DOBAA)_n‐R_F/silica nanocomposites, in which the oligomer contents are 18–72%, were not observed at all even at 800°C, as well as the original silica nanoparticles, although the corresponding sub‐micrometer size‐controlled R_F‐ (DOBAA)_n‐R_F/silica composites (particle size: 359 nm) decomposed completely at 800°C to afford the weight loss in proportion to the content of R_F‐(DOBAA)_n‐R_F oligomer in composites. On the other hand, a slight weight loss of R_F‐(DOBAA)_n‐R_F/silica nanocomposites, in which the oligomer contents are 75–94%, was observed at 800°C compared to that of the original silica nanoparticles. Copyright © 2008 John Wiley & Sons, Ltd.     

UV resistance of encapsulated low molecular weight aromatic compounds in fluoroalkyl end‐capped trimethoxyvinylsilane oligomer/silica nanocomposites

Sol–gel reactions of fluoroalkyl end‐capped trimethoxyvinylsilane oligomer in the presence of low molecular weight aromatic compounds (ArH) such as 1,1′‐bi(2‐naphthol) (BINOL) and 2‐hydroxy‐4‐methoxy benzophenone (HMB) were found to proceed smoothly under alkaline conditions at room temperature to give the corresponding fluorinated oligomeric silica nanocomposites‐encapsulated aromatic compounds (BINOL and HMB) [R_F‐(VM‐SiO₂)_n‐R_F/ArH nanocomposites]. UV light irradiation (λ_max: 254 nm) toward R_F‐(VM‐SiO₂)_n‐R_F/ArH nanocomposites showed that photodegradation of encapsulated ArH was not observed at all in the fluorinated nanocomposites cores, although the parent ArH can exhibit an effective photodegradation behavior under similar conditions. Especially, encapsulated ArH can exhibit no weight loss corresponding to the contents of the aromatic compounds in the fluorinated nanocomposites even after calcination at 800°C. Therefore, fluoroalkyl end‐capped trimethoxyvinylsilane oligomer has high potential for not only the thermal resistance but also the UV resistance fluorinated polymeric materials. Copyright © 2014 John Wiley & Sons, Ltd.     

Preparation and thermal stability of fluoroalkyl end‐capped vinyltrimethoxysilane oligomeric silica/boric acid nanocomposites‐encapsulated a variety of low molecular weight organic compounds

Fluoroalkyl end‐capped vinyltrimethoxysilane oligomer [R_F‐(VM)_n‐R_F] reacted with boric acid to afford the corresponding fluorinated oligomeric silica/boric acid nanocomposite [R_F‐(VM? SiO₂)_n‐R_F/B(OH)₃] fine particles with mean diameter: 36–105 nm. The obtained R_F‐(VM? SiO₂)_n‐R_F/B(OH)₃ nanocomposites were applied to the encapsulation of low molecular weight organic compounds such as diphenylsilanediol, 1,1′‐bi‐2‐naphthol, 4,4′‐biphenol, bisphenol A, bisphenol F, bisphenol AF, biphenyl, dibenzyl, and pentaerythritol into these nanocomposite cores to provide the corresponding fluorinated oligomeric silica/boric acid nanocomposites—encapsulated these organic molecules. Interestingly, the obtained nanocomposites were found to exhibit no weight loss behavior corresponding to the contents of these guest molecules even after calcination at 800 °C, although these nanocomposites were isolated through no purification process. The R_F‐(VM? SiO₂)_n‐R_F nanocomposites—encapsulated these organic guest molecules were prepared under similar conditions. However, it was demonstrated that these nanocomposites can provide the clear weight loss corresponding to the contents of these guest molecules in the nanocomposites after calcination at 800 °C. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3835–3845